Hydrofluoroethers having at least one hydrogenated-OCFX&#39;CH3 end group wherein X&#39;=F, CF3 and their preparation process

ABSTRACT

Hydrofluoroethers of formula: 
     T—CFX′—O—R f —CFX—T′  (II) 
     wherein:  
     T=CH 3 ;  
     X, X′, equal to or different from each other, are selected between F, CF 3 ;  
     T00′=F, Cl, H, C 1 -C 3  perfluoroalkyl, CH 3 , CH 2 OH, COCl, CHO, CO 2 H;  
     R f  is a perfluoroalkylene or a perfluoropolyoxyalkylene and respective preparation process by reduction with hydrogen in the presence of a platinum catalyst supported on metal fluorides of the corresponding compounds with at least one —COCl end group.

[0001] The present invention relates to hydrofluoroethers characterizedin having at least one hydrogenated —OCFX′CH₃ end group wherein X′=F,CF₃ and their preparation process.

[0002] More specifically, the preparation process relates to thereduction with H₂, in the presence of platinum catalysts (Pt), of thecorresponding fluorinated acylchloride precursors.

[0003] Hydrofluoroethers prepared by direct fluorination with F₂ orelectrochemical fluorination of an ether compound or by alkylation offluorinated alcohols are known.

[0004] In patent application WO 99/47,480 it is shwon thathydrofluoroethers can be obtained by alkylation of fluorinated carbonylcompounds. The above methods employ starting compounds having a lowmolecular weight with a number of carbon atoms equal to or lower than12, besides they give low yields and selectivity, and do not givehydrofluoroethers having at least one OCFX′CH, end group with X′=F, CF₃.

[0005] More specifically patent application WO 99/47,480 describes analkylation process of perfluorinated carbonyl compounds in the presenceof a Lewis acid, for example SbF₅. Although in the general formula:

R_(f)—(O—R)_(x)  (I)

[0006] wherein

[0007] R_(f) is a fluorinated C₁-C₁₅ alkyl, optionally substituted andoptionally containing heteroatoms in the chain as N, O, S;

[0008] R is a C₁-C₁₀ alkyl, optionally substituted,

[0009] x ranges from 1 to 3,

[0010] a great number of potential hydrofluoroethers is contained,really by the process only hydrofluoroethers having end groups differentfrom —OCFX′CH₃ are obtainable. See the Examples of patent application WO99/47,480. Therefore the compounds having —OCFX′CH₃ termination have notbeen prepared and no indication about how to prepare them is given.Accordingly the skilled man in the art on the basis of the aforesaidpatent and of the common general knowlegde is unable to prepare thecompounds of the present invention.

[0011] Generally the reaction described in patent application WO99/47,480 proceeds with very low conversions when R_(f) is branched. Thereaction shows the limitation that to obtain acceptable conversions itis necessary to use CH₃F as alkylating agent, has the drawback torequire the use of Lewis acids which are aggressive and need the use ofpressure resistant equipments built in special substances. FurthermoreHF forms, producing further problems in the equipment choice. Since thealkylation reaction is an equilibrium reaction, it does not allow theobtainment of hydrofluoro-ethers with a high yield.

[0012] The Applicant has furthermore found that by using a Lewis acid asSbF₅, in the ratios suggested by patent application WO 99/47,480 and byfollowing the same modalities suggested by the same, nohydrofluoroethers are obtained starting from precursors having aperfluoropolyether structure, in particular containing —OCF₂O—sequences; besides the use of SbF₅ amounts higher than those suggestedcauses the almost total degradation of the initial perfluoropolyetherstructure without obtaining however hydrofluoroethers (see thecomparative Examples).

[0013] The need was therefore felt to obtain hydrofluoroethers by aprocess avoiding the prior art inconveniences and limitations.

[0014] It has been found a hydrogenation process of fluorinatedprecursors containing acylchloride groups carried out in the presence ofplatinum catalysts which allows to obtain hydrofluoroetherscharacterized in having at least one —OCFX′CH₃ end group andquantitative conversions with selectivity even of the order of 70%.

[0015] An object of the present invention are thereforehydrofluoroethers of formula:

T—CFX′—O—R_(f)—CFX—T′  (II)

[0016] wherein:

[0017] T=CH₃;

[0018] X, X′, equal to or different from each other, are selected fromF, CF₃;

[0019] T′=F, Cl, H, C₁-C₃ perfluoroalkyl, CH₃, CH₂OH, COCl, CHO, CO₂H;

[0020] R_(f) is selected from:

[0021] C₂-C₁₅ perfluoroalkylene;

[0022] —(C₂F₄O)_(m)(CF₂CF(CF₃)O)_(n)(CF₂O)_(p)(CF(CF₃)O)_(q)—

[0023] wherein

[0024] the sum n+m+p+q ranges from 2 to 200, the (p+q)/(m+n+p+q) ratiois lower than or equal to 10:100, preferably comprised between 0.5:100and 4:100, the n/m ratio ranges from 0.2 to 6, preferably from 0.5 to 3;m, n, p, q are equal to or different from each other and when m, n rangefrom 1 to 100, preferably from 1 to 80, then p, q range from 0 to 80,preferably from 0 to 50; the units with n, m, p, q indexes beingstatistically distributed along the chain;

[0025] —(CF₂CF₂CF₂O)_(r)— wherein r ranges from 2 to 200,

[0026] —(CF(CF₃)CF₂O)_(s)— wherein s ranges from 2 to 200,

[0027] The preferred structures of the perfluorooxyalkylene chain R_(f)are selected from the following:

[0028] —(CF₂CF₂O)_(m)—(CF₂O)_(p)—

[0029] —(CF₂CF (CF₃)O)_(n)—(CF₂O)_(p)—(CF(CF₃)O)_(q)

[0030] wherein the indexes have the above meanings.

[0031] A further object of the present invention is the preparationprocess of the formula (II) compounds comprising the reduction of theformula (III) corresponding precursors:

T″—CFX′—O—R_(f)—CFX—COF  (III)

[0032] wherein

[0033] T″ is —COCl,

[0034] T′″=F, C₁-C₃ perfluoroalkyl, COCl, H, Cl,

[0035] X, X′, R_(f) are as defined in formula (II),

[0036] carried out with gaseous hydrogen in the presence of a catalystformed by supported platinum, preferably on metal fluorides, preferablyin the presence of inert solvents, at a temperature in the range 20°C.-150° C., preferably 80° C.-120° C., at a pressure between 1 and 50atm, preferably between 1 and 10 atm.

[0037] The formula (III) compounds having at least one —COCl end groupare known, preparable for example by reaction of the corresponding PFPEshaving —COF or —COOH end groups with inorganic chlorides or chlorinatingagents such as thionyl chloride; preferably they are prepared accordingto what described in Italian patent applications MI2002A 001733 andMI2002A 001734 filed at the same time as the present application, andherein incorporated by reference, by a solid-liquid reaction between alarge excess of inorganic chloride, CaCl₂ and a PFPE acylfluoride, at atemperature higher than 100° C., under strong stirring or alternativelya PFPE acylfluoride can be hydrolyzed obtaining the correspondingcarboxylic acid which is subsequently treated with SOCl₂, in thepresence of a tertiary amine, at a temperture in the range 50-100° C.,obtaining the corresponding acylchloride.

[0038] The formula (II) hydrofluoroethers can alternatively be obtainedfrom the corresponding PFPEs having at least one —CHO or—CH(OH)O(CH₂)_(t)R end group wherein t=0 or 1 and R is a C₁-C₁₀ alkylgroup, H, or R_(f).

[0039] The process can be carried out in a continuous or discontinuousway.

[0040] The metal fluorides are preferably selected from the group formedby CaF₂, BaF₂, MgF₂, AlF₃; more preferably CaF₂.

[0041] The Pt concentration on the support is comprised beteeen 0.1% and10% with respect to the total weight of the catalyst, preferably between1% and 2% by weight.

[0042] The used catalyst amount is in the range 1%-100% by weight withrespect to the weight of the formula (III) compound, preferably 10%-100%by weight.

[0043] The inert solvents can for example be linear or cyclicperfluorinated ethers such for example perfluorotetrahydrofuran,perfluorotetrahydropyran, or their mixtures.

[0044] The invention hydrofluoroethers having at least one —OCFX′CH₃ endgroup with X′=F, CF₃ can be used as refrigerants, solvents in cleaningprocesses of printed circuits, and degreasing in vapour phase of metalcomponents as substituents of CFCs, HCFCs and PFCs, resulted harmful forthe ozone layer or show a high GWP (greenhouse potential).

[0045] Besides they found application for the wide range of utilizationtemperatures as substituents of HFCs which in some cases have a limitedapplication as refrigerants due to their very low boiling temperature ortheir very high freezing point.

[0046] The following Examples are given for illustrative and notlimitative purposes of the present invention.

EXAMPLES Example 1

[0047] In a 1,000 ml flask, equipped with mechanical stirrer, bubblingpipe to introduce hydrogen/nitrogen, condenser with a bubble-counter

[0048] 36.7 g of Pt supported on CaF₂ (Pt=1.5% by weight), 400 ml ofmixture 1:1 of perfluorobutyltetrahydrofuran andperfluoropropyltetrahydropyran (D100), are introduced.

[0049] By external heating with thermostated oil bath, the solvent isbrought to the boiling temperature (100° C.), then hydrogen is fed atatmospheric pressure at a flow-rate of 20 l/h, and 36.7 g ofperfluoropolyether (PFPE) acylchloride of formula (IV)

CF₃O(CF₂CF(CF₃)O)_(n)(CF₂O)_(p)CF₂COCl  (IV)

[0050] wherein n/p=25 and n, p are integers such that the number averagemolecular weight is 400, are fed by dropping funnel in 30 minutes.

[0051] When the PFPE-COCl feeding is over, the reduction is let completefor 15 minutes in hydrogen flow.

[0052] It is then cooled to room temperature in nitrogen flow. The rawreaction compound is filtered to recover the catalyst.

[0053] The NMR (¹⁹F and ¹H) analysis of the compound shows a 100%conversion of the starting PFPE-acylchloride and a yield in formula (V)hydrofluoroether of 60% by moles:

CF₃O(CF₂CF(CF₃)O)_(n)(CF₂O)_(p)CF₂CH₃  (V)

[0054] The NMR analysis shows furthermore the resence of the alcoholiccompound of structure (VI) in an amount equal to 40% by moles:

CF₃O(CF₂CF(CF₃)O)_(n)(CF₂O)_(p)CF₂CH₂OH  (VI)

[0055] To separate the hydrofluoroether (V) from the alcohol (VI), theraw reaction compound is chromatographed on silica gel using D 100 aseluent. From the extract, after solvent distillation, 18 g of a compoundare obtained which by the NMR (¹⁹F and ¹H) analysis shows to be thehydrofluoroether of formula (V).

Example 2

[0056] In the same equipment of the Example 1

[0057] 32.5 g of Pt supported on CaF₂ (Pt=1.5%), 150 ml of D100, areintroduced.

[0058] One operates as described in the Example 1, by feeding 38.9 g ofPFPE-acylchloride of formula (VII):

Cl(CF₂CF(CF₃)O)_(n)CF₂COCl  (VII)

[0059] wherein n=3 and the number average molecular weight equal to 647.

[0060] The NMR (¹⁹F and ¹H) analysis of the compound shows a 100%conversion of the starting PFPE-acylchloride and a yield of 70% by molesin hydrofluoroether of formula (VIII):

Cl(CF₂CF(CF₃)O)_(n)CF₂CH₃  (VIII)

[0061] The NMR analysis shows furthermore the presence of the alcoholcompound in an amount equal to 30% by moles, having structure (IX):

Cl(CF₂CF(CF₃)O)_(n)CF₂CH₂OH  (IX)

[0062] To separate the hydrofluoroether from the alcohol, the rawreaction compound is chromatographed on silica gel using D 100 aseluent. From the extract, after solvent distillation, 23 g of a compoundare obtained which by the NMR (¹⁹F and ¹H) analysis shows to be thehydrofluoroether of formula (VIII).

[0063] The experimentation is repeated with the same modalities feedingeach time 38 g of the acylchloride of the Example 2 by using the samecatalyst of the preceding test.

[0064] After a cycle of 10 consecutive tests no variation of thereaction conversion and selectivity has been obtained and therefore nocatalyst deactivation was evident.

Example 3

[0065] In a 100 ml flask equipped with mechanical stirrer, bubbling pipeto introduce hydrogen/nitrogen, condenser with bubble-counter,

[0066] 1 g of Pt supported on C (Pt=5%), 40 ml of D100, are introduced.

[0067] One operates as described in the Example 1, by feeding 3.54 g ofPFPE-acylchloride of the Example 2.

[0068] The NMR (¹⁹F and ¹H) analysis of the compound shows a partialconversion of the starting PFPE-acylchloride (53% by moles) and theconverted compound shows to be a mixture of compounds of which theformula (VIII) hydrofluoroether forms the 64% by moles.

[0069] The difference to 100 is constituted by the acid of formula (X):

Cl(CF₂CF(CF₃)O)_(n)CF₂CO₂H  (X)

Example 4

[0070] In the same equipment of the Example 1

[0071] 30.4 g of Pt on CaF₂ (Pt=1.5%) 150 ml of D100, are introduced.

[0072] One operates as described in the Example 1, by feeding 35.2 g ofPFPE-acylchloride of formula (XI):

ClOCCF₂O(CF₂CF₂O)_(m)(CF₂O)_(p)CF₂COCl  (XI)

[0073] wherein m/p=1 and m, p are such that the number average molecularweight is 2,030.

[0074] The NMR (¹⁹F and ¹H) analysis of the compound shows a 100%conversion of the starting PFPE-acylchloride obtaining a reactionmixture which on an average has 60% by moles of —CF₂CH₃ end groups, 32%of —CF₂CH₂OH end groups, 8% of —CF₂CO₂H end groups.

[0075] From the mixture, after chromatography on silica and solventdistillation, 5.8 g of hydrofluoroether of formula:

CH₃CF₂O(CF₂CF₂O)_(n)(CF₂O)_(m)CF₂CH₃  (XII),

[0076] 12 g of PFPE of formula:

CH₃CF₂O(CF₂CF₂O)_(m)(CF₂O)_(m)CF₂CH₂OH  (XIII),

[0077] 9.7 g of PFPE-alcohol of formula:

HOCH₂CF₂O(CF₂CF₂O)_(m)(CF₂O)_(p)CF₂CH₂OH  (XIV),

[0078] and 2.4 g of PFPE-acid of formula (XV):

HO(O)CCF₂O(CF₂CF₂O)_(m)(CF₂O)_(p)CF₂C(O)OH  (XV),

[0079] are obtained.

Example 5

[0080] In the same equipment of the Example 3

[0081] 3.26 g of Pt on CaF₂ (Pt=1.5%), 40 ml of D100, are introduced.

[0082] One operates as described in the Example 1, by feeding 3.21 g ofPFPE-aldehyde of formula (XVI):

H(O)CCF₂O(CF₂CF₂O)_(m)(CF₂O)_(p)CF₂C(O)H  (XVI)

[0083] wherein m/p=1 and m, p are such that the number average molecularweight is 2,000.

[0084] The NMR (¹⁹F and ¹H) analysis of the compound shows a 100%conversion of the starting PFPE-aldehyde with the obtainment of areaction mixture which on an average has 30% by moles of —CF₂CH₃ endgroups and 70% of —CF₂CH₂OH groups.

Example 6

[0085] In the same equipment of the Example 3

[0086] 2.9 g of Pt on CaF₂ (Pt=1.5%), 40 ml of D100, are introduced.

[0087] One operates as described in the Example 1, by feeding 2.48 g ofhydrated PFPE-aldehyde of formula:

(HO)₂HCCF₂O(CF₂CF₂O)_(m)(CF₂O)_(p)CF₂CH(OH)₂  (XVII)

[0088] wherein m/p=1 and m, p are such that the number average molecularweight is 2,000.

[0089] The NMR (¹⁹F and ¹H) analysis of the compound shows a 100%conversion of the starting hydrated PFPE-aldehyde with the obtainment ofa reaction mixture which on an average has 14% by moles of —CF₂CH₃ endgroups and 86% of —CF₂CH₂OH groups.

Example 7 (Comparative)

[0090] In the same equipment of the Example 3

[0091] 4 g of Pt on CaF₂ (Pt=1.5%), 40 ml of D100, are introduced.

[0092] By operating as described in the Example 1, 4 g of PFPE-alcoholof formula:

Cl(CF₂CF(CF₃)O)_(n)CF₂CH₂OH  (IX)

[0093] are fed, wherein n=3 and number average molecular weight equal to604.

[0094] The compound NMR (¹⁹F and ¹H) shows that no reaction has takenplace, only the PFPE-alcohol of formula (IX) being present.

Example 8 (Comparative)

[0095] In the same equipment of the Example 3

[0096] 4 g of Pt on CaF₂ (Pt=1.5%), 40 ml of D100, are introduced.

[0097] By operating as described in the Example 1, 4 g of PFPE-alcoholof formula:

HOCH₂CF₂O(CF₂CF₂O)_(m)(CF₂O)_(p)CF₂CH₂OH  (XIV)

[0098] are introduced, wherein m/p=1 and m, p are such that the numberaverage molecular weight is 2,000.

[0099] The NMR (¹⁹F and ¹H) of the compound shows that no reaction hastaken place, only the PFPE-alcohol of formula (XIV) being present.

Example 9 (Comparative)

[0100] In the same equipment of Example 3

[0101] 60 mg of Pt black, 40 ml of D100, are introduced.

[0102] By operating as described in the Example 1, 4 g ofPFPE-acylchloride of formula (VII) of the Example 2, are introduced.

[0103] The NMR (¹⁹F and ¹H) of the compound shows that no reaction hastaken place, only the PFPE-acylchloride of formula (VII) being present.

Example 10 (Comparative)

[0104] A 250 ml AISI 316 reactor equipped with magnetic stirring,bubbling pipe, thermocouple for the temperature reading and manometer,is dried at 70° C. under vacuum for 7 hours. It is then transferred indry-box and fed with:

[0105] 47 mg of SbF₅, 10 g of PFPE-acyl fluoride of formula:

FC(O)CF₂O(CF₂CF₂O)_(m)(CF₂O)_(p)CF₂C(O)F  (XVIII)

[0106] wherein m/p=2.13 and m, p such that the number average molecularweight is 1,529.

[0107] The reactor is reassembled in the dry-box and cooled to −80° C.After the reactor has been put under vacuum, 1.82 g of gaseous CH₃CF₃are fed. Then one operates by letting the reaction mixture reach theroom temperature, then heating it to 30° C. and leaving it for 45minutes at said temperature. The reactor is then cooled again to −30° C.and after 20 minutes the reaction mixture is quenched by the addition of8 g of anhydrous methanol. It is brought to room temperature, then thereaction raw compound is discharged from the reactor. The methanolexcess is removed by distillation at reduced pressure. 8.9 g of acompound are obtained, which at the ¹⁹F and ¹H NMR analysis shows to beonly a PFPE-ester of formula:

CH₃OC(O)CF₂O(CF₂CF₂O)_(m)(CF₂O)_(p)CF₂C(O)OCH₃  (XIX)

[0108] i.e. the reaction compound between the starting PFPE-acylfluorideand the methyl alcohol.

[0109] Therefore no formation of hydrofluoroether has been noticed.

Example 11 (Comparative)

[0110] In the same equipment of the Example 10 and proceeding asdescribed in the Example 10, the acid catalyst amount is increased byfeeding:

[0111] 2.2 g of SbF₅, 10.5 g of PFPE-acylfluoride of the Example 10.

[0112] It is cooled to −80° C. noticing a residual pressure of 1.5 bar.One proceeds however as described in the Example 10 by feeding 1.82 g ofCH₃CF₃. A further pressure increase is observed. After quenching withmethanol at low temperature, it is let reach again the room temperature.The gas is sampled and is analyzed by gas-mass. It shows to beconstituted by a mixture of decomposition compounds of thePFPE-acylfluoride chain, having low number average molecular weight(MW≦500).

[0113] None of these shows hydrofluoroether structure with —OCF₂CH₃ endgroups.

[0114] The liquid reaction mass gives only 2.5 g of PFPE-ester offormula:

CH₃OC(O)CF₂O(CF₂CF₂O)_(m)(CF₂O)_(p)CF₂C(O)OCH₃  (XIX)

[0115] wherein m/p=5 and m, p are such that the number average molecularweight is 1,371.

1. Hydrofluoroethers of formula: T—CFX′—O—R_(f)—CFX—T′  (II) wherein:T=CH₃; X, X′, equal to or different from each other, are selectedbetween F, CF₃; T′=F, Cl, H, C₁-C₃ perfluoroalkyl, CH₃, CH₂OH, COCl,CHO, CO₂H; R_(f) is selected from: C₂-C₁₅ perfluoroalkylene;—(C₂F₄O)_(m)(CF₂CF(CF₃)O)_(n)(CF₂O)_(p)(CF(CF₃)O)_(q)— wherein the sumn+m+p+q ranges from 2 to 200, the (p+q)/(m+n+p+q) ratio is lower than orequal to 10:100, preferably comprised between 0.5:100 and 4:100, the n/mratio ranges from 0.2 to 6, preferably from 0.5 to 3; m, n, p, q areequal to or different from each other and when m, n range from 1 to 100,preferably from 1 to 80, then p, q range from 0 to 80, preferably from 0to 50; the units with n, m, p, q indexes being statistically distributedalong the chain; —(CF₂CF₂CF₂O)_(r)— wherein r ranges from 2 to 200,—(CF(CF₃)CF₂O)_(s)— wherein s ranges from 2 to 200,
 2. A processaccording to claim 1, wherein R_(f) is selected from the followingstructures: —(CF₂CF₂O)_(m)—(CF₂O)_(p)—,—(CF₂CF(CF₃)O)_(n)—(CF₂O)_(p)—(CF(CF₃)O)_(q)
 3. A process for thepreparation of the formula (II) compounds of claim 1 comprising thereduction of the formula (III) corresponding precursors:T″—CFX′—O—R_(f)—CFX—T′″  (III) wherein: T″=COCl, T′″=F, C₁-C₃perfluoroalkyl, COCl, H, Cl, X, X′, R_(f) are as defined in formula (II)of claim 1, carried out with gaseous hydrogen in the presence of acatalyst formed by supported platinum, preferably on metal fluorides,preferably in the presence of inert solvents, at a temperature in therange 20° C.-150° C., preferably 80° C.-120° C., at a pressure between 1and 50 atm, preferably between 1 and 10 atm.
 4. A process according toclaim 3, wherein the metal fluorides are selected from the group formedby CaF₂, BaF₂, MgF₂, AlF₃, more preferably CaF₂.
 5. A process accordingto claims 3-4, wherein the Pt concentration on the support is comprisedbeteeen 0.1% and 10% with respect to the total weight of the catalyst,preferably between 1% and 2% by weight.
 6. A process according to claims3-5, wherein the catalyst is used in an amount in the range 1%-100%,preferably 10%-100% by weight with respect to the weight of the formula(III) compound.
 7. A process according to claims 3-6, wherein the inertsolvent is selected among perfluorotetrahydrofuran,perfluorotetrahydropyran, or their mixtures.